SAH and Meningitis

Question 1

What is the epidemiology of SAH ?
Sex ?
Age ?
Mortality rate ?

Answer 1

~6% of all strokes
▪ Slightly more females 1.6:1
▪ Most are under 50
▪ 50% mortality

Question 2

What are risk factors for SAH ?

Answer 2

Hypertension
Smoking
 Excess alcohol consumption Predisposition to aneurysm formation
Family history
Trauma
Cocaine use

Question 3

what are associated conditions for SAH ?

Answer 3

Chronic kidney disease (resultant effect on vessel
wall)
Marfan’s syndrome (effect on connective tissues of
vessels)
Neurofibromatosis (unclear mechanism, if any link)

Question 4

What is the most common pathology for SAH ?

Answer 4

rupture of an aneurysm in the circle of Willis

Question 5

What can cause aneurysm ?

Answer 5

genetic predisposition- absence of tunica media and lamina

haemodynamic effects at branch points in the circle of willis

Question 6

what is the most common type of aneurysm in SAH?

Answer 6

Berry

Question 7

list the most common site to least of Aneurysms for SAHs

Answer 7

30% - Anterior communicating artery proximal anterior
cerebral artery
Posterior communicating artery (25%)
Bifurcation of the middle cerebral artery as it splits
into superior and inferior divisions (20%)

Question 8

what can be affected if Anterior communicating artery / proximal anterior
cerebral artery is affected in SAH ?

Answer 8

Can compress the nearby optic chiasm and

may affect frontal lobe or even pituitary

Question 9

what can be affected if posterior

cerebral artery is affected in SAH ?

Answer 9

Can compress the adjacent oculomotor
nerve causing an ipsilateral third nerve
palsy

Question 10

why do physiological changes happen in SAH ?

Answer 10

Bleeding into the subarachnoid space

Question 11

what are early brain injury changes seen in SAH ? Why?

Answer 11

Microthrombi - these may occlude more distal branches
Vasoconstriction - Blood in CSF irritating arteries
Cerebral oedema - Inflammatory response to hypoxia
Apoptosis

Question 12

what are cellular changes seen in SAH ?

Answer 12

Oxidative stress
Release inflammatory mediators - microglia
platelet activation

Question 13

what are systemic complication of SAH ? what system is particularly activated ?

Answer 13

Sympathetic activation-
Early cushing response
Myocardial necrosis - sympathetic response
Inflammatory response

Question 14

what is the headache seen in SAH ? describe what the patient will say

Answer 14

thunderclap 
onset is explosive and severe
worst headache I ve ever had 
diffuse pain 
lasts hours - wks

Question 15

what other symptoms are present in SAH ?

Answer 15

LOC , Confusion , Dizzy, Meningism (Neck stiffness, photophobia ), focal neurology, history of sentinel bleed , cardiac arrest

Question 16

What investigations need to be done in SAH ?

Answer 16

CT head
If confirmed = CT angiogram
Lumbar puncture

Question 17

what would CT look like in SAH ?

Answer 17

Prominent filling of the basal cisterns in a five pointed
‘star’ pattern
Blood may be seen within the ventricles (maybe due to
reflux from subarachnoid space)

Question 18

How would you undertake a lumbar puncture ?

Answer 18

1. find iliac crest
2. find L4/5
3. insert needle between spinous process
4. Feel give of lig flavum
5. feel give of dura
6. remove needle stylet and collect CSF

Question 19

what are LP findings in SAH ?

Answer 19

increased opening pressure
Bloody/ Xanthochromia
High protein
high red cell

Question 20

what is xanthochromia ?

Answer 20

yellow colouring of the
CSF due to metabolism of haemoglobin to
bilirubin within the subarachnoid space
 Seen at least 12 hours post bleed
More specific than frank blood for
SAH (helps exclude a
bloody/traumatic tap)

Question 21

what are LP findings in viral Meningitis ?

Answer 21

clear/cloudy appearance
Normal/ raised protein
High lymphocyte count

Question 22

what are LP findings in bacterial Meningitis ?

Answer 22

Cloudy
High protein
low glucose
high white cell = neutrophils

Question 23

what is treatment approach for SAH ?

Answer 23

ABC

support airway , give oxygen , fluid and nimodipine to alleviate cerebral vasospasm

Question 24

what in neuro obvs are you looking out for ?

Answer 24

signs of raised ICP

Question 25

what neruosurgcial options are their for SAH ?

Answer 25

Craniectomy - decompression Coiling - platinum wire into the aneurysm = thrombosis of blood clipping- spring clip around the neck of the aneurysm, causing it to lose blood supply and ‘shrivel up’

Question 26

what are causative organisms in neonates for meningitis?

Answer 26

E. coli Group B streptococcus Listeria monocytogenes

Question 27

what are causative organisms in children for meningitis?

Answer 27

Haemophilus influenzae type B (HiB vaccine given, ‘meningococcus’) Neisseria meningitidis

Question 28

what are causative organisms in the elderly for meningitis?

Answer 28

``` Streptococcus pneumoniae (vaccines now given) Listeria monocytogenes ```

Question 29

what are risk factors for meningitis ?

Answer 29

``` CSF defects (e.g. spina bifida) Spina procedures (e.g. surgery, lumbar puncture) Endocarditis (as a focus of bacteraemia) Diabetes (immunosuppression) Alcoholism Splenectomy (immunosuppression) Crowded housing (students at risk) ```

Question 30

what is the presentation of meningitis ?

Answer 30

Headache • Neck stiffness (nuchal rigidity) • Photophobia with fever

Question 31

what are Associated symptoms of meningitis ?

Answer 31

Flu like symptoms, stiffness, photophobia, seizure, meningococcal rash (non- blanching), altered mental state, shock. In babies- rigidity, bulging fontanelle, crying

Question 32

outline the pathophysiology of meningitis

Answer 32

Nasophyarngeal bacteria enter circulation Bateramia = damage to vessel in the Brain and meninges = Enters SA space = Multiply in SA space . Vasospasm = cerebral infarction Inflammation = Increased CSF resistance = Hydrocephalus increase BBB Pearmeabilty = Oedema = raised ICP == decreased cerebral blood flow

Question 33

why is Maculopapular rash seen in meningococcal septicaemia?

Answer 33

``` microvascular thrombosis due to many factors, including Sluggish circulation Impaired fibrinolysis Increased tissue factor expression in endothelial cells ```

Question 34

what investigation to take for suspected Meningitis ?

Answer 34

bloods - cultures and PCR Lumbar puncture CT is non-resolving Sepsis screen - CXR and MSU

Question 35

What is the supportive treatment for meningitis ?

Answer 35

Analgesia • Antipyretics • Fluids if shocked

Question 36

what is medical treatment of meningitis ?

Answer 36

IV ceftriaxone • Dexamethasone to prevent hearing loss (due to swelling of vestibulocochlear nerve or effect on cochlea) if virial - Aciclovir = herpes Ganciclovir for CMV

Question 37

what are complications of Meningitis ?

Answer 37

Septic shock (due to bacteraemia) Disseminated intravascular coagulation (due to bacteraemia) Coma (due to raised ICP) Cerebral oedema (due to cerebral inflammation) Raised ICP Death (due to brain herniation, sepsis) SIADH (maybe direct effect on hypothalamus/pituitary?) Seizures (due to irritation of brain parenchyma) Hearing loss (due to swelling of vestibulocochlear nerve or cochlea itself. Perilymph is continuous with subarachnoid space) Intellectual deficits (due to direct brain damage) Hydrocephalus (due to interruption of CSF drainage pathways and effect on arachnoid granulations) Focal paralysis (maybe due to cerebral abscess)